1. Field of Invention
This invention pertains to the field of earth and mining working equipment. More particularly, this invention pertains to an earth and mining bit block which is configured for mounting on earth displacement equipment and to receive a bit for penetrating hardened earth, rock and mining materials.
2. Description of the Related Art
It is well known in the art of earth and mining working equipment that replaceable bits are used for engaging the material to be removed. These bits are typically received within a bit block which is carried by the earth working equipment. Depending upon the particular piece of equipment, the bit blocks may be received on a chain attachment or rotatable drum device utilized for trenching, drilling, boring in rock and mining. A cutting tool or bit is either rotatably received within or welded into the bit block, depending upon the particular application. Typically, it is the practice to rotatably mount the bit in the bit block in order to accomplish a more even wear on the bit and to prolong its useful life. When the bit becomes worn down from excavation and mining, the penetrator is removed from the bit block and replaced.
A conventional bit block 10P, as illustrated in PRIOR ART FIG. 1, is configured for mounting a bit 60. While there are various configurations of a conventional bit block 10P, a conventional bit block includes generally a block adapted to be received on selected earthworking or mining equipment 66, and a receptor formed in the block for receiving the shank 62 of a bit 60. Typically, the receptor 14P is defined by a through opening whereby a portion of the distal end 64 of the shank 62 extends through the bit block 10P in order to receive a retainer clip (not shown) for securing the bit 60 in the bit block 10P. Other conventional bit blocks are described in Kennametal's Catalog “Chain and Wheel Trenching Tools” (Fall 2001).
A conventional bit block 10P defines an engagement surface 38P for engaging the equipment 66 to which it is to be secured. The bit block 10P is typically mounted on the equipment 66 by welding about the perimeter 40P of the engagement surface 38P. Illustrated in FIG. 1, the bit block 10P is welded to a chain 68. While illustrated as being welded to a chain 68, it is well known that inherent problems exist with respect to protecting the distal end 64 of the bit 60 when the bit block 10P is welded to a drum or other conventional apparatus, as well, and specifically related to the build up of excavated material. It is well known in such applications that the top portion of the chain 68 typically has at least a small amount of slack, which allows the chain 68 to sag. As a result, it is a common problem that the bolts 70 used to secure the individual panels into the chain 68, in some situations, creates an undesirable engagement between the distal end 64 of the bit shank 62 and the bolts 70. After repeated incidents of engagement, the distal end 64 of the bit shank 62 becomes deformed, thereby making removal of the bit 60 difficult, if not impossible.
A conventional bit block 10P further defines a leading surface 34P whose furthermost point is coincident with the leading edge of the engagement surface 38P. As illustrated in FIG. 1, the leading surface 34P of the bit block 10P is substantially orthogonal with the engagement surface 38P.
Typically, in order to remove materials excavated by the bit 60, rakes 80 are installed between pairs of horizontally aligned bit blocks 10P. As the chain 68 is driven, the rakes 80 collect materials and move them outside the working area.